Not really. We wouldn't have know how madara survived vote and history of chakra but each to his own.
Well we learned How Madara survived through Black Zetsu not Kaguya. Hagoromo should have been the source of the tie in to all chakra as we were led to believe before this Kaguya reveal.
I wouldn't have had an issue with kaguya if :
1) she wasn't introduced so late in the series. When we first heard Hagoromo's and Madara's name it was back in part I and the begining of Part 2. and they were mentioned several times with peices of themselves existing into the modern ninja world (the Rinnegan for Hagorom and Obito posing as Madara) so their appearance was not only welcomed by foreshadowed. Kaguya was mention at the end of the juubito arc and she appeared some 5 chapters later with little to know history. Barely uttered more than 3 sentences and then was sealed again and forgotten. This is why everyone feels there is so much unfinished about her and the story.
2.) As mentioned above she seemed more like a mindless puppet to Black Zetsu than a woman of her own. Maybe if she had been that shadow of a figure guiding Madara from the get go her appearance wouldn't have felt...forced on us.
3.) The history of chakra as you mentioned, came from the tree. It was believed that Hagoromo was the progenitor of humans using chakra so it really wasn't necessary for their to be a Kaguya.
I think Kishi mainly introduced Kaguya because he really had no way of stopping Madara whom he made far too powerful thus using the deus ex machina bailout to defeat him.
But as you said to each his/her own